Ignition-device for a bomb



Nov. 15, 1966 T. A. FIETELAARS IGNITION-DEVICE FOR A BOMB Filed Aug. 6, 1964 INVENTOR. 75 s ado/4+ AF'ef/aars BY W of gwzag 7"7a me 3 United States Patent 3,285,170 IGNITION-DEVICE FOR A BOMB Theodorus Adrianus Fietelaars, The Hague, Netherlands, assignor to Fijn Mechanische Industrie Beckers Sons N.V., Brummen, Netherlands Filed Aug. 6, 1964, Ser. No. 387,957 Claims priority, application Netherlands, Aug. 6, 1963, 296,285 Claims. (Cl. 1027) Ignition-devices for a bomb whereby a spring loaded striking pin operates a detonator, said bomb being provided with a membrane activated by hydraulic pressure, should be considered well-known from practice.

The object of the invention is to provide an ignitiondevice with which a very accurate and reliable adjustment can be obtained, such that it allows a bomb thrown into water to be detonated exactly at a predetermined depth.

A further object of the invention is to provide an ignition-device enabling to obtain an adjustment also adapted to being used for very different depths and yet very accurate for each individual depth.

As should appear from the following a bomb provided with an ignition-device according to the invention is very reliable whereas a blind bomb will lose its detonating capacity after it has been left in water for some time.

Finally so arranging the new ignition-device, respectively incorporating it in the entirety, is aimed at that an easy to handle construction is achieved.

The ignition-device according to the invention is characterized in that a striking spring loaded striking pinholder is temporarily blocked with respect to an activating rod connected to the membrane, which blocking can be released in that the activating rod is moved contrary to the action of an adjustable depth regulating spring.

A very efficient embodiment is obtained by arranging a depth regulating spring inside the striking pin-holder, said depth regulating spring exerting a spring loaded pressure to the activating rod which is guided in a fixed enclosing socket, in the wall of which socket at least an aperture is provided, a ball being located in said aperture, said ball resting against the activating rod and which ball extends into a cavity in the striking pin-holder, whereas the activating rod is narrowed at a location further spaced from the striking pin behind the ball.

Preferably the striking pin can be screwed into the striking pin-holder and then can be fixed therein in different positions. Previously the position corresponding with a determinate pressure of the depth regulating spring can be adjusted, which pressure in turn corresponds with the hydraulic pressure (therefore water depth) exerted to the membrane, at which pressure the activating rod starts moving. As practice has shown thismakes a very accurate adjustment possible.

The invention and some of its embodiments are explained more in detail with the help of the drawing in which an embodiment of the new depth bomb in longitudinal section is shown.

In practice the charge case 1 with the explosive main charge proper, for safety reasons, is kept separately from the ignition mechanism. Only shortly before operating the bomb the detonator 2 and the ignition mechanism are connected with the charge case. So the situation of the ready to be launched bomb in fully mounted position is shown.

The detonator-holder 3 can be connected to the chargecase 1 by soldering or for example in case an anti-magnetic construction is required a folded connection can be applied. Drawn is the case in which the detonator 2 with the help of a spring 4 with bent end 5 is held in the bore of the detonator-holder 3. Said spring 4 is held with reice spect to the detonator-holder by a screw 6. Since exclusive rights are claimed for this way of holding in a patent application filed simultaneously with the present patent application, said way of holding the detonator is not further explained.

More particularly the present invention refers to the ignition-device by which at the desired moment the striking pin 7 hits the detonator 2. Said striking pin 7 is under the influence of a strongly tensioned striking spring 8, which is kept tensioned until the moment of the striking pin having to see to the initial ignition of the detonator by hitting the percussion-cap.

The striking spring 8 is kept under tension between on the one side a collar 9 of an enclosing socket 10 positioned within the case 19 and on the other hand a collar 12 of the striking pin-holder 13. Said striking pin-holder 13 is longitudinally movable with respect to the enclosing socket 10, however balls 14 hamper such movement. Said balls 14 of which at least one should be present are partly positioned in a cavity 15 in the wall of the striking pin-holder and lean, since they rest in bores 11 of the enclosing socket, against a rod 16, called activating rod. So the stop balls 14 prevent the striking pin-holder 13 from moving in the direction of the detonator under the pressure of the striking spring 8. However, said movement is possible when in a way still to be described the activating rod 16 is moved in the direction of the detonator 2. As soon as a small diameter portion 17 of the activating rod gets flush with the balls 14 the balls, under the influence of the tensioned striking spring 8, are pressed into the narrowed portion 17 of the activating rod and this to such extent as to allow the striking pin-holder 13 to move in the direction of the detonator 2, since then the effect of the stop balls is neutralized. Said removal occurs vigorously since the strongly pretensioned spring 8 is allowed to ease quite suddenly, causing the striking pin 7 to hit the percussion-cap of the detonator 2 with utmost force. Preferably the wall portion of the cavity 15 contacting the balls 14 should be slightly sloping as shown in the drawing. I

The activating rod 16 can be moved in the direction of the detonator 2 contrary to the action of a so-called depth regulating spring 18. According to the drawn embodiment said spring acts on a collar of the activating rod 16 and the striking pin 7 and so is positioned inside the striking pin-holder 13 into which also one end of the activating rod 16 extends.

' The striking pin, the striking pin-holder as well as the enclosing socket 10 for the activating rod 16 all are comprised in a fully closed case 19. Said case 19 widening at its front is closed by a transformable membrance 20 resting with its thickened edge 21 in a groove of the case 19 and being enclosed therein by a cover 22 which is preferably screwed on. A adjusting ring 23 may be applied between the cover 22 and the membrane-edge.

In a corresponding way the case 19 may be widened near the detonator-holder 3 which may be screwed on the screw thread of the case portion widened at 24, if required also interposing a sealing ring 25.

Designing the case 19 at least approximately in the drawn diabolic shape has special advantages. Then the case has at its both ends a diameter which is larger than in the centre where the case only needs to comprise the striking pin-holder and the enclosing socket. The diabolic shape is a very favourable one since in that way a very practical handle for launching the bomb is obtained. The narrower portion of the case may possibly be provided with so-called grip-grooves and so forms a favourable resting-place for the hand.

The membrane 20 is connected to the activating rod 16 by means of a support 26 and a clamping ring 27 between which the membrane 20 is clamped. So any movement of the membrane is transmitted to the activating rod 16. The cup-shaped flange 9 of the enclosing socket 10 is screwed into a narrowed portion 28 of the front end of case 19. So said enclosing socket will always remain in place.

Some apertures 30 are provided in the cover 22 of the case 19 for admitting water to the membrane, the latter being of the so-called rolling membrane-design. The end of the activating rod 16 extends into an aperture of the cover 22. Said end is provided with a groove while forming a widened head 31 under which a sliding fork 32 can pass. In pushed-in position said fork keeps the activating rod in place. Pulling away the fork causes the activating rod to move in the direction of the detonator 2. Further so-called Seeger-rings 33, 34 are provided in grooves of the activating rod 16 for securing the membrane. Said removal occurs under the influence of the hydraulic pressure exerted to the membrane as the bomb is thrown into the water. The hydraulic pressure depends on the actual depth position of the bomb. By adjusting the pressure of the depth regulating spring 18 the pressure applied to the membrane can be made to surpass the pressure of the spring 18 at a determinate hydraulic pressure corresponding with a determinate depth in the water. This results in a removal of the activating rod which in consequence makes the balls 14 to pass into the narrowing 17 in the way described and the striking pin to be removed vigorously by said hydraulic pressure.

In order to prevent the air from being compressed in the space between the membrane and the cup-flange 9 some apertures 35 are provided in said flange.

The striking pin-holder is centered in the case 19 by a collar 37 provided with air passage apertures 36. The striking pin 7 is screwed in the striking pin-holder 13 and can be secured therein by pinching the rearmost thin portion of the striking pin-holder against the flattened circumference of the striking pin. The depth regulating spring 18 encompasses a turned-01f portion of the striking pin 7 and in a corresponding Way the turned-off end of the activating rod 16.

In a determinate depth regulating spring an accurate adjustment can be obtained of the pressure required to move the activating rod in the direction of the detonator by which the striking pin-holder is released, by the extent to which the striking pin 7 is screwed into the striking pin-holder. So the ignition-mechanism can such accurately be adjusted that a bomb will explode at a determinate even small depth. By applying a stronger depthregulating spring the bomb can be made to explode only at greater depths as a so-called depth-bomb.

In case a bomb hasbeenadjusted for exploding at a determinate depth and when the bomb should come at a shallower point, for example near the beach; it could possibly explode later as the tide is making and therefore at a quite undesired moment. This can-be prevented by taking care that the rest of the closed case can gradually fill up with water. So when the bomb has not exploded at the required moment it loses its explosive capacity. When the case is water-logged the pressure on both sides of the membrane is equal and so the striking pin-holder cannot be released. For such purpose the screw-connections can e.g. be made to leak to some extent. Further a narrow labyrinth-shaped groove can be turned in the bottom of the case also. In this way at changes of temperature the pressure inside the then not hermetically sealed case remains the same so that the depth regulation remains absolutely constant.

I claim:

1. An ignition device for a bomb comprising a casing to be attached to a charge having a detonator, a hydraulic pressure responsive membrane attached to one end of said casing, a firing pin located within said casing, 21 firing pin holder enclosing said pin, an activating rod connected to said membrane for activating said firing pin, an adjustable depth regulating spring located in said firing pin holder coacting with said firing pin and said activating rod maintaining said activating rod inoperative until a predetermined depth of water has been obtained, an enclosing socket surrounding said activating rod fixed to said casing, a firing spring coacting with said socket and said pin holder, means for locking said firing pin holder to said enclosing socket and means upon said activating rod when moved by a pressure on said membrane greater than the pressure of said regulating spring for releasing said locking means whereby said firing pin holder and pin are moved by said firing spring to detonate said detonator.

2. An ignition-device according to claim 1 wherein said locking means comprises a construction wherein said socket has an aperture therein and said firing pin holder has a cavity, a ball located in said aperture resting against said activating rod and extending into said cavity, and said activating rod in narrowed at a location spaced behind said ball so that said ball may be withdrawn from said cavity.

3. An ignition device as set forth in claim 1 wherein said firing pin may be adjustably fixed in said firing pin holder at different positions.

I 4. An ignition device as set forth in claim 1 wherein said enclosing socket is provided with a cylindrical collar provided with air passage apertures.

5. An ignition device according to claim 1 wherein said casing is provided with an enlarged portion at each end having screw threads for securing to said charge and said membrane.

References Cited by the Examiner UNITED STATES PATENTS 1,368,569 2/1921 Minkler 1027 1,514,743 11/1924 Taylor l027 2,43 8,117 4/ 1948 Ellwood.

2,859,696 11/1958 Burg 1027 BENJAMIN A. BORCHELT, Primary Examiner.

SAMUEL W. ENGLE, Assistant Examiner. 

1. AN IGNITION DEVICE FOR A BOMB COMPRISING A CASING TO BE ATTACHED TO A CHARGE HAVING A DETONATOR, A HYDRAULIC PRESSURE RESPONSIVE MEMBRANE ATTACHED TO ONE END OF SAID CASING, A FIRING PIN LOCATED WITHIN SAID CAUSING, A FIRING PIN HOLDER ENCLOSING SAID PIN, AN ACTIVATING ROD CONNECTED TO SAID MEMBRANE FOR ACTIVATING SAID FIRING PIN, AN ADJUTABLE DEPTH REGULATING SPRING LOCATED IN SAID FIRING PIN HOLDER COACTING WITH SAID FIRING PIN AND SAID ACTIVATING ROD MAINTAINING SAID ACTIVATING ROD INOPERATIVE UNTIL A PREDETERMINED DEPTH OF WATER HAS BEEN OBTAINED, AN ENCLOSING SOCKET SURROUNDING SAID ACTIVATING ROD FIXED TO SAID CASING, A FIRING SPRING COACTING WITH SAID SOCKET AND SAID PIN HOLDER, MEANS FOR LOCKING SAID FIRING PIN HOLDER TO SAID ENCLOSING SOCKET AND MEANS UPON SAID ACTIVATING ROD WHEN MOVED BY A PRESSURE ON SAID MEMBRANE GREATER THAN THE PRESSURE OF SAID REGULATING SPRING FOR RELEASING SAID LOCKING MEANS WHEREBY SAID FIRING PIN HOLDER AND PIN ARE MOVED BY SAID FIRING SPRING TO DETONATE SAID DETONATOR. 